140 



MUSCINE& 



The non-sexual propagation of mosses takes place in a variety of 

 ways, the first step being, in nearly all cases, the production of a colour- 

 less filament of the nature of a protoneme. This protonemal branch, like 

 the true protoneme which springs from a spore, may produce by lateral 

 budding a number of leafy shoots. Protonemal branches of this kind 

 are in some genera (such as Mnium, L., Barbula, Hedw., and Phascum, 



L.) produced in large num- 

 bers simply by turning over 

 a tuft of moss on the soil. 

 In this state they frequently 

 hibernate, the portion above 

 the soil disappearing entirely. 

 In some mosses the leaves 

 produce a protoneme simply 

 by the growth of particular 

 cells into segmented fila- 

 ments ; and this may even 

 take place with detached 

 leaves if kept moist. The 

 seta or stalk of the sporogone 

 has a special tendency to 

 produce protonemes when 

 in contact with damp soil. 

 Rhizoids also may give rise to 

 gemmae or leaf-buds, whether 

 above or beneath the surface 

 of the soil. Gemma of a more 

 complicated structure occur 

 in a few species, as Aulacom- 

 nion androgynum (Schw.) 

 (Bower, 'Journ. Linn. Soc.,' 

 1884, xx., p. 465), and Tetra- 

 phis pellucida (Hedw.), being 

 stalked fusiform or lenticular 

 multicellular bodies. In the 



latter species they are enveloped in an elegant cup or cupule, composed of 

 a number of leaves, out of which they eventually fall, and then put forth 

 protonemal filaments, which give rise first to a flat prothallus resembling 

 that of a fern, and then to a leaf-bud. Gemmae are produced in a variety 

 of situations, as at the apex of a leaf and on the rhizoids. 



The sexual organs of mosses are very commonly enveloped in closely 

 crowded leaves which have undergone a certain amount of modification, 



FIG. 105. 4, young plant of Barbula, in ', //, rhizoid, 

 producing protonemes /, and underground gemma k 

 ( x 20). , the same gemma ( x 300). (After Goebel.) 



